libgimp: rename "Save|Load Defaults" buttons in GimpProcedureDialog.

The term "Defaults" is not clear enough and looks like it may be
redundant with the "Factory Defaults" button. Let's try an alternative
"Save Settings" and "Load Saved Settings".

Also adding some tooltips.

And finally making the "Load Saved Settings" only sensitive if the "Save
Settings" button had been used at least once.

libgimp/gimpprocedureconfig-private.h

@@ -23,6 +23,8 @@
 #define __GIMP_PROCEDURE_CONFIG_PRIVATE_H__
 
 
+gboolean   gimp_procedure_config_has_default   (GimpProcedureConfig  *config);
+
 gboolean   gimp_procedure_config_load_default  (GimpProcedureConfig  *config,
                                                 GError              **error);
 gboolean   gimp_procedure_config_save_default  (GimpProcedureConfig  *config,

libgimp/gimpprocedureconfig.c

@@ -908,6 +908,22 @@ gimp_procedure_config_get_file (GimpProcedureConfig *config,
   return file;
 }
 
+gboolean
+gimp_procedure_config_has_default (GimpProcedureConfig *config)
+{
+  GFile    *file;
+  gboolean  success;
+
+  g_return_val_if_fail (GIMP_IS_PROCEDURE_CONFIG (config), FALSE);
+
+  file = gimp_procedure_config_get_file (config, ".default");
+
+  success = g_file_query_exists (file, NULL);
+  g_object_unref (file);
+
+  return success;
+}
+
 gboolean
 gimp_procedure_config_load_default (GimpProcedureConfig  *config,
                                     GError              **error)

libgimp/gimpproceduredialog.c

@@ -52,6 +52,7 @@ struct _GimpProcedureDialogPrivate
   GimpProcedureConfig *initial_config;
 
   GtkWidget           *reset_popover;
+  GtkWidget           *load_settings_button;
 
   GHashTable          *widgets;
   GHashTable          *mnemonics;
@@ -234,7 +235,8 @@ gimp_procedure_dialog_constructed (GObject *object)
                            "padding", 3, NULL);
   gtk_widget_show (hbox);
 
-  button = gtk_button_new_with_mnemonic (_("_Load Defaults"));
+  button = gtk_button_new_with_mnemonic (_("_Load Saved Settings"));
+  gtk_widget_set_tooltip_text (button, _("Load settings saved with \"Save Settings\" button"));
   gimp_procedure_dialog_check_mnemonic (GIMP_PROCEDURE_DIALOG (dialog), button, NULL, "load-defaults");
   gtk_box_pack_start (GTK_BOX (hbox), button, FALSE, FALSE, 0);
   gtk_widget_show (button);
@@ -242,8 +244,12 @@ gimp_procedure_dialog_constructed (GObject *object)
   g_signal_connect (button, "clicked",
                     G_CALLBACK (gimp_procedure_dialog_load_defaults),
                     dialog);
+  gtk_widget_set_sensitive (button,
+                            gimp_procedure_config_has_default (dialog->priv->config));
+  dialog->priv->load_settings_button = button;
 
-  button = gtk_button_new_with_mnemonic (_("_Save Defaults"));
+  button = gtk_button_new_with_mnemonic (_("_Save Settings"));
+  gtk_widget_set_tooltip_text (button, _("Store current settings for later reuse"));
   gimp_procedure_dialog_check_mnemonic (GIMP_PROCEDURE_DIALOG (dialog), button, NULL, "save-defaults");
   gtk_box_pack_start (GTK_BOX (hbox), button, FALSE, FALSE, 0);
   gtk_widget_show (button);
@@ -1271,6 +1277,8 @@ gimp_procedure_dialog_save_defaults (GtkWidget           *button,
                   error->message);
       g_clear_error (&error);
     }
+  gtk_widget_set_sensitive (dialog->priv->load_settings_button,
+                            gimp_procedure_config_has_default (dialog->priv->config));
 }
 
 static gboolean